In a typical roofing system, metal or wood trusses are used to support a roof assembly. Such trusses typically include a variety of support members including a top chord supported at an angle by a plurality of web members extending from a bottom chord. A plurality of trusses can be placed atop a building frame in a parallel spaced apart arrangement such that the slope of the top chords defines the pitch of a roof.
Additional support members, referred to as purlins, are sometimes incorporated atop the truss top chords in a spaced apart parallel arrangement and in a direction perpendicular to the top chords. Such purlins typically help support the downward vertical loads of a heavy roof assembly, such as barrel roof tiles, and help provide ventilation. Prior art purlins include dimensional lumber and formed sheet metal with right angle bends having Z, C, S, or top hat-shaped cross sections that include a generally vertical web located between top and bottom legs (used for attaching the purlin to rafters and roof panels).
Such roofing systems are designed to meet certain performance requirements, such as vertical resistance to dead loads as required under local building codes. Such performance depends upon a variety of factors, including the type, thickness, and spacing of the trusses, and roof panels, as well as the type and placement of fasteners used. Such performance is measured by a variety of organizations that test roof assemblies.
The installation of typical roofing systems is labor intensive. In a typical construction, the purlins are attached to the top chords and roof panels by screw fasteners. While such screw fastening techniques are suitable for their intended purpose and result in acceptable performance, when correctly applied, the use of screw fasteners is time consuming when compared to installations using nail fasteners, which can be quickly installed by auto-nailers such as pneumatic nail guns. This is especially evident when considering the number of fasteners required for large roofing jobs can require the installation of more than sixty-eight (68) fasteners per four by eight foot (4′×8′) roof panel. Further, it is a common problem that when screw fasteners are over-applied they drill out the metal framing members intended to be connected, thereby rendering the connection inadequate.
In addition to the installation of the trusses and roof panels, a fascia and soffit are commonly attached to the truss heel. In the prior art, the starter-terminator purlin, fascia, and soffit are separate pieces installed separately at the eave. For example, a starter-terminator purlin can be installed by one worker, a fascia by another worker at another time, and the soffit by still another worker at another time. Installing each of these structures separately is time consuming and inevitably leads to one worker getting in the way of another and requires separate set up for each installation. Furthermore, it can be difficult to make a water resistant, if not waterproof, seal between these separate pieces.